Tap connector and setscrew therefor



June 22, 1965 A. SCHIFFMANN J J TAP CONNECTOR AND SETSCREW THEREFOR Filed Feb. 19. 1962 FIG. 3.

VENTOR AL SCHIFFMANN av WIM+W ATTORNEYS United States Patent 3,191,139 TAP CQNNECTOR AND SETSCREW THEREFOR Alois Schithnann, Streitfeldstrasse, Munich 8, Germany Filed Feb. 19, 1962, Ser. No. 174,130 Claims prioriw, application Germany, Apr. 17, 1961, Sch 29,562; Dec. 18, 1961, Sch 37,030 10 Claims. '(tCl. 339-97) The present invention relates to tap connectors for electrically connecting a branch line or cable to a main line or cable and to setscrews for such connectors. More specifically the invention relates to bow shaped tap connectors wherein the main line is held between the arms of said bow and is pressed against one of said arms by means of at least one setscrew held in a thread hole of the other arm, and wherein the branch line is held fixed in a hole of the connector body.

Such connectors are especially useful for, but are not limited to, tapping the through lines in power cables. At the taps there is usually little space available, since for safety and practical reasons it is essential to open the cable only along a short portion thereof, thus affording little space for bending the hot lines apart. In spite of the above it heretofore was necessary to make the tap connectors rather bulky so that the pressing force exerted by one or more setscrews did not unduly bend apart the arms of the connector, thus impairing the electrical contact and the mechanical connection between the line and the tap connector.

It is, therefore, a major object of the invention to provide a tap connector which is relatively lightly built and which at the same time allows the application of setscrew forces large enough to assure proper mechanical and electrical contact.

It is a further object of the present invention to improve the setscrews used in such connectors so that they can establish good electrical contact between the line, particularly between an insulated line, and the connector.

Conventional setscrews usually comprise in their end facing the cable a straight cutting groove which tends to twist the line wire or wires and which is quickly clogged by insulating material removed from the line. The cloging, of course, impairs the making of good electrical contacts. Hence it is a further object of the invention to provide these setscrews with improved cutting grooves which avoid said twisting and which permit the insulating material to be removed from the grooves.

It is a further object of the invention to provide these setscrews with means which prevent a wire, particularly a thin wire, from being pressed aside within the connector by the setscrew motion.

It is a further object of the invention to provide at least one of the arms of the tap connector with means which, in cooperation with the setscrew or screws, improve the electrical contact and the fixed mechanical position of the line in the connector.

The above objects have been achieved in accordance with one aspect of the invention by a tap connector which comprises a body having two arms forming a bow, the free ends of said arms being held together by a clamp, a line or wire being held fixed within said bow by at least one setscrew having cutting grooves in its end facing the line or wire, the depth of said grooves increasing from the center of the screw towards its periphery.

dhlldd Patented June 22, 1965 Further improvements of the setscrew according to the invention reside in making the grooves narrow relative to the screw diameter and having the grooves slope relative to the longitudinal axis of the screw and contrary to the direction of screw motion. Another advantage resides in forming the end face of the setscrew with a concave recess.

Tap connectors are known in the art, having two members one member holding one of the lines therein, the other member being attached to the first member by means of screws which also hold the other line between the two members. These known connectors are rather bulky and it is diiiicult to connect them to a live wire. Moreover loosening of the screws disconnects the two members as well as the line. The invention removes these drawbacks.

The invention, its objects, and advantages will appear more clearly from the following specification and accompanying drawings in which:

FIG. 1 is a side view of one embodiment of a tap connector according to the invention,

FIG. 2 shows a plan view of the connector of FIG. 1,

FIG. 3 is a sectional side view of another embodiment,

FIG. 4 is a front view of the connector according to PEG. 3,

FIG. 5 is a sectional plan view along the line VV of FIG. 3,

FIG. 6 is a side view of still another embodiment of a novel tap connector having a setscrew according to the invention,

FIG. 7 is an end view showing the end face of the setscrew shown in FIG. 6,

FIG. 8 is a partial longitudinal section through the screw in FIG. 7 taken along line XX,

FIG. 9 is an enlarged longitudinal section through the end of a setscrew according to the invention,

FIGS. 10 and 11 show plan views of connectors having a plurality of setscrews.

FIGS. 1 and 2 show a tap connector having body 40 with arms 1 and 2 forming a bow adapted to receive a line (not shown) between the arms. Arm 2 has at least one thread hole therein for receiving setscrew 3 which has slot 4 in its end face 41, which slot acts as a cutting means for penetrating and removing insulation from the line.

Arm 1 comprises on its inner surface cutting edges 5 extending perpendicularly to the plane of the drawing and pointing towards end face 41 of screw 3. Body 40 comprises aperture 6 adapted to receive a branch line (not shown) which is held in place by setscrew 7.

In accordance with the invention, the free ends of arms l and 2 are held together by clamp 8 which is provided with inwardly bent edges 9 and 10. These edges 9 and 10 grip into grooves 11 and 12 provided in the free ends of arms 1 and 2.

The tap connector is attached to a main line by placing the line between arms 1 and 2 and then pushing clamp 8 in the longitudinal direction of the cable into engaging relationship with grooves 11 and 12. Screw 3 is then tightened and arms 1 and 2 cannot be forced apart because clamp 8 holds them together. This feature of the invention has the advantage that considerable screw pressure can be applied to a rather lightly built tap connector. A further advantage is that clamp 8 prevents the line wire 3 from being pushed aside when screw 3 is tightened, thus assuring that large contact areas are obtained between the connector and the line and in turn provide good electrical contact.

FIGURES 3, 4 and 5 show anotherembodiment of the invention. Here the tap connector comprises body 50 having arms 21 and 22 of a shape slightly different from the shape of arms 1 and 2. Arm 22 receives set-screw 23 having cutting slot 24 in its end face 51. The inner surface of arm 21 is provided witha plurality of cutting spikes 25 pointing towards said end face 51-. Aperture 26 in body 50 receives a branch cable held in place by screw 27. Clamp 28 is provided with openings 29 and 30 adapted to receive protrusions 31 and 32 at the free ends of arms 21 and 22. The protrusions have outwardly bent ends 33and 34 which lock the clamp 28 in' position. a

To place clamp 28 into position after the line has been put between arms 21 and 22, it 'is necessary to bend the arms toward each other slightly. This assures looking of clamp 28 even before screw 23 is tightened. Of course, when removing clamp 28, arms 21 and 22 are also bent slightly towards each other. In the embodiment of'FIG. 1, arms 1 and 2 need not be bent to place clamp 8 in position because clamp 8 is always held tightly to the free ends of arms 1 and 2 by edges 9 and 10 and grooves 11 and 12, which cooperate as the members of a dovetail joint. In addition, this cooperation assures proper seating of clamp 8, even if a'large force is applied to the connector by means of screw 3.

crease during operation.

FIG. 6 shows a still further embodiment of the invention comprising novel tap connector means and 'novel setscrew means. This connector has body 60 with arms 61 and 62. Arm 62 receives setscrew. 63. Free end 64 of arm .62 comprises hinge means'65 hinging one end of clamp. 66 to arm 62. The other end of clamp 66 is bent over to form hook 67- which grips behind groove 68 of arm 61. Arm 61 is slightly bent towards arm 62 to let hook ,67 snap into groove 68. Arm 61 comprises cutting edges 69 which extend transversely. to the longitudi nal axis of a cable rather than parallel to the cable axis as do cutting edges 5' shown in 'FIG. .1.

Screw 63 comprises end faceT70' in which there is provided cutting groove 71' for cutting and removing cable or line insulation. In accordance with the invention, the width of cutting groove 71 is small relative to the diameter of screw 63. For example, groove 71 "can have a width about the diameter of screw 63. This narrownessof the groove prevents twisting of the wire by the screw, since the diameter of the wire is usually larger than the width of the groove.

The groove extends substantially in the direction. of the longitudinal axis of the screw, and its depth, which ismeasured along the axis, increases, from the center to the periphery of the screw. Thisfeature assures that the groove provides more space for removed insulating material where it tends most to accumulate, namely at the periphery of the screw. A further advantage of this feature resides vin the inclined bottom of the groove which permits "the .insulating material removed to 'be pushed out of the grooves.

As can be seen inFlG. 6, groove 71 is inclined or' slopes with respect to the longitudipaljaxis of screw 63 ,FIG. 7 showing variable depth 72 ofvgroove 71 increasing from the center of screw 63 to its periphery.

FIG. 9 shows an improved setscrew 73 having end face 74 provided with concave recess 75. Radius R of recess 75 is slightly shorter in length than twice the diameter since these sloping grooves op-v porting it.

. 4 of screw 73. Of course, screw 73 also comprises at least one cutting groove 76.

FIGS. 10 and 11 show plan views of tap connectors 77 and 80. In FIG. 10 there is one setscrew 78 for the main line and two setscrews 79 for the branch line.

In FIG. 11, connector 80 comprises two setscrews 78 for the main line and two setscrews 79 for the branch line.

By way of example and without limiting the scope of the appended claims, arms 1, '2; 21, 22;-61, 62 are preferably adapted t receive main lines having a bare wire diameter from about 0.3 to 0.6" whereas the apertures for the branch line are large enough to receive lines having a bare wire diameter from about,0.1" to 0.4". It is preferable to make the connectors of brass alloys and the setscrews of copper alloys. The connector according to the invention is particularly suitable for insulated lines to which it can be,eonnectedby using insulated tools'without the necessity of shutting off the line voltage. Thespikes'o'r the cutting edges penetrate the line insulation thus contacting the bare wire and directly sup- Hence, it is assured. that any softening or complete removal of the insulating material caused by heat'or the like does not affect the proper seating of the line in the connector, and the screw pressure cannot de- The clamp furthermore assures that a relatively light connector may be used for insulated lines which, due to their insulation, require substantial pressure for the screw and spikes or cutting edges to penetrate the insulation and to bear directly against the bare wire.

It is to be understood that the present invention is by no means limited to the particular embodiments and measurements described and shown but als comprises any modification within the scope of the appended claims.

Wha'tlclaimis:

1. A tap connector for electrically connecting'a branch line to an insulated main through line, said connector comprising acne-piece body having a 'rear portion and two arms with free ends, said rear portion connecting the arms to form a bow for receiving said insulated line between ,the arms and incontact with at least one of the arms, said rear portion comprising means for connecting said branch line to said body, said connector further comprising a clamp forremo-vably engaging with said free ends of the arms, one of said arms having at least one threaded hole and a setscrew in the threaded hole for pressing said insulated line into contact with the other ofsaid arms, said setscrew com-prising a bolt having a head, a threaded shank, and an end face opposite said head, said setscrew further having'cut-ting grooves shaped for cutting and removing line insulation, said grooves being of narrow width relative to the diameter of 'said'shank, deep, open to said shank periphery and end face, the other arm of said connector comprising means'opposite said threaded hole for'contacting said line, said-clamp closing the bow and limiting any yielding of said arms away from each other upon tightening of the setscrew. I i

2. A tap connector according to claim 1, wherein said setscrew has cutting grooves whose depth in the direction of the longitudinalaxis of thesetscrew increases from the center'of said threaded shank to the' periphery thereof,

so that said grooves have aninclined bottom.

r 3. "A tap connector according t-ofclaiin-l, wherein said groovesare inclinedrelative toe-the longitudinal axis of the shank-and contrary to the direction. of tightening screwmotion.

4. A tap connector according to claim 1, wherein the end'face of said setscrew/further" comprises aconcave recess.

5, A tap connector-accordingto claim 4, wherein said concave'recessof'said end face has a radius of curvature less than twice the diameter of said setscrew.

A p. c nn ctor a c rdingtocla m w erein ea h of the two arms comprises an outwardly opening groove at its free end, said clamp comprising inwardly bent edges fitting into the groove of each arm.

7. A tap connector according to claim 1, wherein each of the two arms comprises a protrusion at its free end,

said clamp comprising apertures therein through which the free ends of the arms extend in how closing-position, said protrusion of each arm locking the clamp in position.

8. A tap connector according to claim 1, wherein one of the arms comprises hinge means at its free end for hinging one end of the clamp to said one arm, the free end of the other .arm comprising means for holding the other end of the arm in locked position.

9. A tap connector according to claim 1, wherein said other arm comprises a plurality of spikes for establishing contact with the main line.

10. A tap connector according to claim v1, wherein the other arm comprises a plurality of cutting edges for establishing contact with the main line.

References Cited by the Examiner UNITED STATES PATENTS 1,495,017 5/24 Gentsch 339-264 1,968,736 7/34 Bodendieck 339-2-64 X 2,107,835 2/38 Pierce 339-244 6 5/ 38 Buchanan 339-272 6/ 38 Tipsord 3'39-264 5/ 39 Olson 85-47 4/40 Buchanan. 4/40 Lee 339-97 12/41 Ebby 339-97 4/46 Allen 151-70 3/49 Simmons 151-70 3/50 Cafiero 339-272 5/50 Berman 85-47 10/50 Frank 339-97 2/59 Lemke 85-47 3/59 Bonnet et a1. 339-272 3/ Moore. 5/60 Kobryner et a1. 339-272 9/60 Hubbell et .al 339-97 10/62 Cornell 339-97 X 12/ 63 Sorflaten 339-272 FOREIGN PATENTS 3/ 31 France. 5/59 France. 12/2 1 Germany.

JOSEPH D. SEERS, Primary Examiner. 

1. A TAP CONNECTOR FOR ELECTRICALLY CONNECTING A BRANCH LINE TO AN INSULATED MAIN THROUGH LINE, SAID SAID CONNECTOR COMPRISING A ONE-PIECE BODY HAVING A REAR PORTION AND TWO ARMS WITH FREE ENDS, SAID REAR PORTION CONNECTING THE ARMS TO FORM A BOW FOR RECEIVING SAID INSULATED LINE BETWEEN THE ARMS AND IN CONTACT WITH AT LEAST ONE OF THE ARMS, SAID REAR PORTION COMPRISING MEANS FOR CONNECTING SAID BRANCH LINED TO SAID BODY, SAID CONNECTOR FURTHER COMPRISING A CLAMP FOR REMOVABLY ENGAGING WITH SAID FREE ENDS OF THE ARMS, ONE OF SAID ARMS HAVING AT LEAST ONE THREADED HOLE AND A SETSCREW IN THE THREADED HOLE FOR PRESSING SAID INSULATED LINE INTO CONTACT WITH THE OTHER OF SAID ARMS, SAID SETSCREW COMPRISING A BOLT HAVING A HEAD, A THREADED SHANK, AND AN END FACE OPPOSITE SAID HEAD, SAID SETSCREW FURTHER HAVING CUTTING GROOVES SHAPED FOR CUTTING AND REMOVING LINE INSULATION, SAID GROOVES BEING OF NARROW WIDTH RELATIVE TO THE DIAMETER OF SAID SHANK, DEEP, OPEN TO SAID SHANK PERIPHERY AND END FACE, THE OTHER ARM OF SAID CONNECTOR COMPRISING MEANS OPPOSITE SAID THREADED HOLE FOR CONTACTING SAID LINE, SAID CLAMP CLOSING THE BOW AND LIMITING ANY YEILDING OF SAID ARMS AWAY FROM EACH OTHER UPON TIGHTENING OF THE SETSCREW. 